Preparation Of One-dimensional Fe/C Composites And Their Microwave Absorption Performancer

With the rapid development of electromagnetic technology,electronic equipments has created great convenience for human production and life.At the same time,it also brings serious electromagnetic radiation pollution problems.Microwave wave absorbing materials?MAMs?can solve the problem of electromagnetic pollution fundamentally.Among many electromagnetic wave absorbing materials,magnetic carbon-based MAMs are always considered as the most promising candidates for their relatively low density,improved chemical stability,as well as compatible/tunable magnetic loss and dielectric loss.Herein,melamine is employed as carbon source and one-dimensional structure Fe/C composites are successfully prepared through a simple pyrolysis method.The effects of pyrolysis temperature and metal-doped on its chemical composition and microstructural feature are systemically discussed.The factors affecting its microwave wave absorbing properties are further analyzed.Pea-like Fe/Fe₃C nanoparticles embedded in N-doped carbon nanotubes?Fe/Fe₃C@NCNTs?are obtained by direct pyrolysis method.Pea-like microstructure gives them unique superiority for the dissipation of electromagnetic waves through electron vibration along the axial direction.Resaerch resoults have shown that with the increase of pyrolysis temperature,the formation of Fe₃C is inhibited,and the mass percentage of carbon component is decreases.Compared with previous reported magnetic carbon-based MAMs,Fe/Fe₃C@NCNTs composites have a good balance between dielectric loss and magnetic loss,and their absorption ability is less sensitive to the pyrolysis temperature and they can preserve their efficient microwave wave absorbing properties in the temperature range of 600oC-700oC.Fe/Fe₃C@NCNTs-600 exhibits an excellent electromagnetic wave absorption ability and its maximum reflection loss value is-46.0 dB at 3.6 GHz?d=4.97 mm?and the qualified bandwidth reach up to 14.8 GHz with the integrated thickness from 1.00 to 5.00 mm.In order to further improve the electromagnetic wave absorption performance of Fe/Fe₃C@NCNTs composites,pea-like Fe/Fe_0.64Ni_0.36 nanoparticles embedded in N-doped carbon nanotubes composites(Fe/Fe_0.64Ni_0.36@NCNTs)were synthesized by nickel doping.A large amount of Fe/Ni heteroatomic interfaces exist these composites,which could increase the complex permittivity by the effect of electron transfer and spin polarization.The research results show that pyrolysis products with molar ratios of FeCl₃·6H₂O and NiCl₂·6H₂O of 95:5 and 90:10 have excellent impedance matching characteristics and good electromagnetic wave absorption performance,and their maximum reflection loss values are-72.0 dB?6.8 GHz,2.7 mm?and-28.7 dB?18.0 GHz,1.1 mm?,and qualified bandwidth are 15.0 GHz?3.0 GHz-18.0 GHz?and 15.2 GHz?2.8GHz-18.0 GHz?,respectively.These researches can provide new experimental ideas for the research and development of magnetic carbon-based MAMs.